It occurred to me that this would be good to have as a widget, but I’m not sure if it’s possible for a widget to fetch a live image from a URL. I haven’t been able to find any examples of how to do it, so I’m guessing it might not be possible.
I did put together a Shortcut that does ‘get contents of URL’ followed by a Quick Look, so that’s something at least, but a widget would be preferable, if possible.